The Academy's Evolution Site
Biological evolution is one of the most fundamental concepts in biology. The Academies have been active for a long time in helping people who are interested in science comprehend the concept of evolution and how it permeates every area of scientific inquiry.
This site provides teachers, students and general readers with a variety of educational resources on evolution. It contains key video clips from NOVA and WGBH produced science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol that symbolizes the interconnectedness of life. It is used in many cultures and spiritual beliefs as symbolizing unity and love. It also has important practical applications, like providing a framework for understanding the evolution of species and how they react to changes in the environment.
The first attempts at depicting the world of biology focused on separating organisms into distinct categories which were distinguished by their physical and metabolic characteristics1. These methods, which relied on the sampling of various parts of living organisms or sequences of short fragments of their DNA greatly increased the variety of organisms that could be included in a tree of life2. However, these trees are largely composed of eukaryotes; bacterial diversity is not represented in a large way3,4.
By avoiding the necessity for direct experimentation and observation genetic techniques have allowed us to depict the Tree of Life in a more precise way. Trees can be constructed by using molecular methods, such as the small-subunit ribosomal gene.
Despite the dramatic expansion of the Tree of Life through genome sequencing, a lot of biodiversity remains to be discovered. 에볼루션 무료 바카라 is particularly true of microorganisms, which are difficult to cultivate and are often only represented in a single sample5. A recent study of all known genomes has produced a rough draft version of the Tree of Life, including a large number of bacteria and archaea that have not been isolated, and which are not well understood.
This expanded Tree of Life is particularly useful for assessing the biodiversity of an area, helping to determine if certain habitats require special protection. This information can be used in a variety of ways, including finding new drugs, fighting diseases and improving the quality of crops. This information is also extremely valuable to conservation efforts. It can aid biologists in identifying the areas most likely to contain cryptic species with important metabolic functions that could be at risk of anthropogenic changes. While funds to protect biodiversity are essential however, the most effective method to protect the world's biodiversity is for more people in developing countries to be equipped with the knowledge to act locally to promote conservation from within.
Phylogeny
A phylogeny (also called an evolutionary tree) depicts the relationships between organisms. Scientists can construct a phylogenetic diagram that illustrates the evolutionary relationships between taxonomic categories using molecular information and morphological differences or similarities. The role of phylogeny is crucial in understanding the relationship between genetics, biodiversity and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms with similar traits that evolved from common ancestral. These shared traits can be either analogous or homologous. Homologous traits are similar in their evolutionary origins while analogous traits appear like they do, but don't have the identical origins. Scientists group similar traits together into a grouping known as a Clade. Every organism in a group have a common trait, such as amniotic egg production. They all came from an ancestor that had these eggs. A phylogenetic tree is then constructed by connecting the clades to identify the organisms who are the closest to one another.
For a more detailed and accurate phylogenetic tree scientists make use of molecular data from DNA or RNA to establish the relationships between organisms. This information is more precise and gives evidence of the evolutionary history of an organism. Researchers can utilize Molecular Data to estimate the evolutionary age of organisms and identify the number of organisms that have the same ancestor.
The phylogenetic relationships between species are influenced by many factors, including phenotypic flexibility, a kind of behavior that alters in response to specific environmental conditions. This can cause a characteristic to appear more similar to one species than another, obscuring the phylogenetic signals. However, this issue can be solved through the use of methods such as cladistics that incorporate a combination of analogous and homologous features into the tree.
In addition, phylogenetics helps determine the duration and rate at which speciation takes place. This information will assist conservation biologists in deciding which species to protect from extinction. In the end, it's the preservation of phylogenetic diversity which will lead to a complete and balanced ecosystem.
Evolutionary Theory
The central theme in evolution is that organisms change over time as a result of their interactions with their environment. Many scientists have come up with theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism could evolve according to its own requirements, the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy and Jean-Baptiste Lamarck (1844-1829), who believed that the use or absence of traits can cause changes that are passed on to the
In the 1930s & 1940s, ideas from different fields, such as genetics, natural selection and particulate inheritance, were brought together to create a modern theorizing of evolution. This describes how evolution is triggered by the variations in genes within the population and how these variations alter over time due to natural selection. This model, known as genetic drift or mutation, gene flow and sexual selection, is a key element of current evolutionary biology, and is mathematically described.
Recent discoveries in the field of evolutionary developmental biology have revealed that variation can be introduced into a species via mutation, genetic drift, and reshuffling genes during sexual reproduction, as well as by migration between populations. These processes, as well as other ones like directional selection and genetic erosion (changes in the frequency of an individual's genotype over time) can result in evolution that is defined as change in the genome of the species over time, and the change in phenotype over time (the expression of that genotype in an individual).
Students can gain a better understanding of the concept of phylogeny through incorporating evolutionary thinking into all aspects of biology. In a recent study conducted by Grunspan and co. It was found that teaching students about the evidence for evolution boosted their understanding of evolution during a college-level course in biology. For more details on how to teach about evolution, see The Evolutionary Potency in All Areas of Biology or Thinking Evolutionarily as a Framework for Integrating Evolution into Life Sciences Education.
Evolution in Action
Scientists have traditionally studied evolution through looking back in the past, analyzing fossils and comparing species. They also study living organisms. But evolution isn't a thing that occurred in the past. It's an ongoing process, taking place right now. Viruses evolve to stay away from new medications and bacteria mutate to resist antibiotics. Animals alter their behavior in the wake of the changing environment. The changes that result are often visible.
It wasn't until late 1980s when biologists began to realize that natural selection was in play. The main reason is that different traits result in a different rate of survival and reproduction, and can be passed down from generation to generation.
In the past, if one particular allele--the genetic sequence that determines coloration--appeared in a group of interbreeding organisms, it could quickly become more prevalent than all other alleles. As time passes, that could mean that the number of black moths in a population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
It is easier to observe evolution when a species, such as bacteria, has a high generation turnover. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that descend from a single strain. Samples of each population have been collected regularly and more than 500.000 generations of E.coli have passed.
Lenski's research has demonstrated that mutations can alter the rate of change and the effectiveness of a population's reproduction. It also demonstrates that evolution takes time, a fact that many are unable to accept.
Another example of microevolution is that mosquito genes for resistance to pesticides appear more frequently in populations where insecticides are used. This is due to the fact that the use of pesticides creates a selective pressure that favors those with resistant genotypes.
The rapidity of evolution has led to an increasing appreciation of its importance especially in a planet which is largely shaped by human activities. This includes the effects of climate change, pollution and habitat loss, which prevents many species from adapting. Understanding the evolution process can assist you in making better choices regarding the future of the planet and its inhabitants.